With the spread of personal computing devices and the advent of digital media, there is increased concern of copyright owners to limit the distribution of copyrighted materials. The use of digital media allows users to easily share and distribute the copyrighted materials, such as music, movies, and the like. As users distribute the digital media, the copyright owners lose income from sales and/or licenses.
In an attempt to limit the distribution, access control technologies, e.g., digital rights management (“DRM”), have evolved. Access control technologies attempt to limit the distribution or the use of the copyrighted materials to only those individuals who have a purchased/licensed the materials and therefore have a right to use the materials (e.g., play the music or movie).
One attempt to limit use and/or distribution includes a key authentication approach. Generally, a key authentication approach limits the use of copyrighted materials to only those machines that possess a proper decryption key. The key authentication approach, however, is vulnerable to an attack on the key.
Another approach is the use of digital watermarks. Digital watermarks are digital signatures that are added to the media during production or distribution. Digital watermarks, like the key authentication approach, are not robust and may be rendered useless.